Leptospirosis is considered to be the most widespread zoonotic disease in the world. Human disease is acquired primarily through contact with water contaminated with the urine of infected wild or domestic animals. Leptospirosis is recognized as an emerging infectious disease in the US, where it has caused extensive outbreaks associated with flooding and fresh water recreation. In less developed countries, leptospirosis is a major public health problem as the cause of substantial morbidity and mortality among subsistence farmers and urban slum dwellers. Because few laboratories are equipped to perform the antiquated microagglutination test upon which diagnosis now depends, it is well recognized that human leptospirosis is an under-recognized disorder. To date there is no effective prevention for leptospirosis. Leptospiral infections can be treated with inexpensive antimicrobial agents. However, timely treatment is considered to be essential to prevent disease progression to renal or hepatic failure, and/or massive pulmonary hemorrhage. The major obstacle to successful treatment is the difficulty in making an early and accurate diagnosis. The goal of the research proposed here is the development of a rapid, point-of-care diagnostic test for human leptospirosis, based upon the innovative proprietary lateral flow technology (DPP, Dual Path Platform) of the investigator organization, Chembio Diagnostic Systems Incorporated. Development of the test will be made possible by collaboration with Weill Medical College of Cornell University and the Oswaldo Cruz Foundation in Brazil - the largest research institution in Latin America. The collaborating investigators have developed unique leptospiral antigens that will be used in the proposed work. The two specific aims of the Phase I studies will result in a prototypic test and establish the feasibility of proceeding into Phase II evaluations: 1. Using a novel antigen screening method developed by Chembio (termed MAPIA); the most seroreactive antigens recognized during the acute phase of leptospirosis will be identified. 2. A combination of the most seroreactive antigens will be used to develop a prototype lateral flow diagnostic test to detect the greatest number of acute-phase patients, while avoiding antigens recognized by control subjects. The point-of-care diagnostic to be developed here could revolutionize clinical practice by allowing the first medical provider in contact with a potential patient to make an immediate diagnosis of leptospirosis and initiate treatment. Lateral flow tests are highly suitable for use in developing countries, as well as in a variety of field or community settings, because they require no equipment to use, are room temperature stable, and have long shelf lives. Furthermore, these features also make this type of test ideal for epidemiological investigations. [unreadable] [unreadable] [unreadable]